Day two at the AAAS meeting brought more interesting debate and discussion. Bright and early first thing in the morning Greg Scholes, from the University of Toronto, Canada, filling in for Graham Fleming, from the University California, Berkeley, who was ill, said that we have to learn lessons from nature on solar light harvesting.

A great venue with a gloomy backdrop!

He describes himself as a quantum biologist – someone who probes natural structures on the quantum scale to try to understand what makes them tick – and says that we have to learn from millions of years of evolution to improve the ways in which we capture light energy. He points to green sulfur bacteria that live in the Black Sea at a depth of 80m that can still survive by harvesting what little light there is down there. By probing these sorts of light harvesting complexes using ultra-short laser pulses scientists can learn how to more efficiently gather light energy and transfer it to where it is needed.

We were up in the clouds next, as Ravi Ravishankara, director of the chemical sciences divison of the earth system research laboratory of the National Oceanic and Atmospheric Administration in the US, took us on a whirlwind tour of aerosols. Unfortunately, the effect of aerosols on the climate is still something of a black box, he explains, and we’re missing quite a bit of the information we need. The net effect of aerosols on the climate is thought to be roughly the same as carbon dioxide, thanks to aerosols like black carbon, which can absorb heat, or others which can damage the ozone layer. Vikki Grassian, from the University of Iowa, US, says that the error bars in our understanding of how atomspheric aerosols affect climate are big. She says the problem is complex as aerosols come from so many sources, have different lifetimes, undergo different chemistry, so atmospheric chemists are trying to build a database. Obviously, trying to cover all the aerosols and their reactions would be a sisyphean task. ‘You try to study the most important reactions, you try to use chemical intuition,’ she adds, ‘I’m not going to study methane, it’s not going to do anything, it’s pretty inactive.’ It’s up to chemists, she says, to use their box of analytical tools to work out which reactions are going on and take this to the modellers so they can plug the effects into their models.

Up in the press room we were given a lesson in improving on what Mother Nature has already given us – food crops. We all know more food will be needed in the coming decades to feed a growing global population with increasingly eclectic tastes. Howard Griffiths, professor of plant ecology at the University of Cambridge, UK, is one of the scientists at the forefront of this huge challenge. He’s attempting to ‘turbocharge’ plants to improve yields and is looking at a number of ways to do this. One of the principal ways he’s trying to do this is by changing crop plants like potatoes and wheat to harness carbon dioxide using the C4 pathway – to produce a four carbon organic acid – rather than the less efficient C3 pathway they currently use. This change could increase light harvesting efficiency from 4% to 6% and, although that might not sound like much, is huge if that increase could be carried over into crop yields. He’s also looking at other ways to improve the enzyme Rubisco, which fixes carbon dioxide into sugars, using strategies such as parking it in subcellular components where it can be suffused in more carbon dioxide.

The view from the press room. Chemistry is everywhere!

Richard Cogdell at the University of Glasgow, UK, is pursuing a different strategy and is trying to learn from photosynthesis to make synthetic fuels. They’re trying to use electricity to drive fuel production by harnessing synthetic biology technology. In his group they’re trying to take carbon dioxide and turn it into terpenes – energy dense organic compounds already produced by many plants. They also have the advantage of being immiscible with water, which should make them much easier to harvest than other biofuels such as ethanol. Cogdell describes this type of work as ‘one of the grand challenges mankind faces’ and says that young researchers need to be enthused and sold this opportunity to shape the future of the world. I think we can all agree with those sentiments.

Patrick Walter

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